1. Field of the Invention
The present invention relates to a tilt adjustable type steering apparatus for a vehicle, which prevents a release of tilt adjusted position fastening at a secondary collision.
2. Related Background Art
A tilt adjustable type steering apparatus capable of adjusting a tilt angle of a steering wheel, corresponding to a physique, a driving posture, etc. of a driver is, as disclosed in, e.g., Japanese Patent Application Laid-Open No.11-198821, constructed such that a rear column member is so connected in a swayable or rockable manner to a rear side end of a front column member fixed to a car body (which is a so-called swing tilt).
FIGS. 12 through 14 illustrate the tilt type steering apparatus disclosed in Japanese Patent Application Laid-Open No.11-198821 given above. FIG. 12 is a rear view (showing the front as viewed from the rear of the vehicle, wherein a partial sectional view therein shows a section taken along the line A—A in FIG. 13) of the tilt type steering apparatus for the vehicle in the prior art. FIG. 13 is a vertical sectional view of the tilt type steering apparatus for the vehicle in the prior art. FIG. 14 is a bottom view of the tilt type steering apparatus for the vehicle in the prior art.
A steering shaft is divided into a front steering shaft 1 and a rear steering shaft 2, which are connected by a universal joint 3. The front steering shaft 1 and the rear steering shaft 2 are rotatably accommodated in a front column member 4 and a rear column member 5, respectively.
The rear column member 5 is connected in the swayable manner to a rear portion of the front column member 4 fixed to the car body. The rear column member 5 is so structured as to be swayable or rockable within a tilt adjustable range about a tilt center C. Note that the tilt center C is concentric with the universal joint 3.
A fixed gear 6 having a gear teeth portion 6a is fixed to an undersurface of the front column member 4. A movable gear 8 having a gear teeth portion 8a meshing with the gear teeth portion 6a of the fixed gear 6 is pivotally supported in the swayable or rockable manner around on a pivot 7 provided in the rear column member 5. Note that the respective gear teeth portions 6a, 8a are arranged circularly around the tilt center C.
A reaction member 9 is extended in a car-width direction below the movable gear 8. A wedge-shaped member 10 having a tapered surface 10a for pressing a rear tapered surface of the movable gear 8 in a way that abuts and slides on this rear tapered surface, is so disposed as to be movable in back-and-forth directions between the movable gear 8 and the reaction member 9.
A compression coil spring (a length-expansion coil spring) 11 is disposed between a rear side end of the wedge-shaped member 10 and an extended piece 8b extending from the movable gear 8. The compression coil spring (the length-expansion coil spring) 11 gives a bias to the gear teeth portion 8a of the movable gear 8 through the wedge-shaped member 10 at all times in such a direction that the gear teeth portion 8a of the movable gear 8 and the gear teeth portion 6a of the fixed gear 6 mesh with each other. The compression coil spring (the length-expansion coil spring) 11 has, however, a function of biasing the movable gear 8 through the extended piece 8b in a releasing direction when in tilt releasing.
A tilt lever 12 is formed integrally on both sides of the rear portion of the wedge-shaped member 10 and extends in the car-widthwise direction. The tilt lever 12 is swayable about a lever rotation center pin 12a provided on the rear column member 5.
Note that a support spring (a length-expansion coil spring) 13 is disposed between the front column member 4 and the rear column member 5. This configuration prevents descents of the rear column member 5, the steering wheel, etc. when the two gears 6, 8 disengage from each other.
Further, the fixed gear 6 is fixed to the front column member 4 by bolts 14, 15, whereby the gear meshing can be adjusted.
In a tilt lock mechanism constructed described above, when making a tilt adjustment, the tilt lever 12 is swayed or moved backwards of the vehicle, against the biasing force of the compression spring (the length-expansion coil spring) 11, thereby retreating the wedge-shaped member 10 backwards.
As a result, the movable gear 8 which is assisted by the biasing force of the compression spring (the length-expansion coil spring) 11 is thereby rotated and thus disengages from the fixed gear 6. With this arrangement, the tilt releasing can be attained.
The tilt adjustment is effected in a way that tilts the rear column member 5 within the tilt adjustable range adapted to driving of the vehicle.
After making the tilt adjustment, upon a release from the tilt lever 12, the tilt lever 12 is swayed forwards of the vehicle by the biasing force of the compression spring (the length-expansion coil spring) 11, thereby moving the wedge-shaped member 10 forwards.
As a result, the gear teeth portion 8a of the movable gear 8 is pressed against and firmly meshed with the gear teeth portion 6a of the fixed gear 6 by dint of the wedge-shaped member 10 biased by the compression spring (the length-expansion coil spring) 11. This enables tilt fastening.
Incidentally, according to the tilt lock mechanism described above, the tilt lever 12 which is formed integrally on both sides of the rear portion of the wedge-shaped member 10, extends in the car-widthwise direction and is swayable substantially in the horizontal direction about the lever rotation center pin 12a provided perpendicularly to the rear column member 5.
In particular, as shown in FIGS. 12 and 14, a handle portion 12b, for an operator, of the tilt lever 12 is comparatively largely protrudes sideways of the two column members 4, 5. The tilt fastening/releasing operations are done by swaying this handle portion 12b substantially in the horizontal direction.
As a result, when the rear column member 5, etc. gets collapsed and this moves forwards of the vehicle upon a secondary collision of the vehicle, an instrument panel impinges on the handle portion 12b of the tilt lever 12 that protrudes sideways, and the tilt releasing might occur.